I was told about how babies would be placed in a fire to be burned to death in honor of their god, and that there may have been been singing while this happened. Is there any truth to this, and what other ceremonies do we know of?
Hello there! The answer to your question depends on which Baal you're talking about and which scholars you ask. The name itself (Phoenician: b‘l) simply means "lord," and so the Baal of the Old Testament may be shorthand for a range of deities, though some experts believe that it refers to a specific god. At any rate, my knowledge on this particular topic is limited to Carthage and other Phoenician-Punic sites in the Western Mediterranean. That's what I'll focus on below.
The chief deity at Carthage was Baal Hammon (b‘l ḥmn). Scholars aren't quite sure what the name means. Possibilities include "lord of the perfume altars" or "lord of the furnaces," but the late Serge Lancel thought ḥmn meant "baldaquin" or "small chapel," with the implication that Baal Hammon was the "paternal deity, the protector of government but also the guarantor of the issue and durability of families." Now, it's still a matter of controversy whether the Carthaginians actually sacrificed infants to Baal. Archaeologists have uncovered thousands of urns containing the calcified remains of children and infants, and this originally seemed to corroborate references to the practice in the Bible and various Greek sources (Roman authors almost never mention it, surprisingly). After analyzing the physical material, however, some experts have concluded that the alleged victims actually died of natural causes and that the urns were interred in a special cemetery for infants. Yet according to the most recent study (or at least the most recent one I've read), the remains belonged to infants who had perished well after the average period of death by natural causes, which would again suggest that the Carthaginians practiced child sacrifice. On top of that, in some of the surviving dedications, the parents apparently describe their offering as a "sacrifice of their own flesh" (mlk ’dm bšrm btm).
If this was indeed a normal practice, we still don't really know what happened during the ritual. The notion that there was music and noise-making stems mainly from an uncritical mishmashing of the ancient literary sources, popularized by French writers until the 1960s. To quote Gilbert and Collete Picard, for example:
The ceremony took place at night, by moonlight. In the precinct stood a bronze statue of [Baal Hammon] and at his feet a pit was dug in which a fire or topheth was lit. Around the statue stood the assistants and the parents of the victims, the musicians, and the dancers. A priest would bring the child 'dedicated' to the god, already killed according to 'secret rites', and lay him in the statue's arms from which he would roll into the flames. Then flutes, tambourines, and lyres would drown the cries of the parents and lead the dancers into a wild dance. There was, in fact, a taboo which forbade the assistants to see, cry out, or listen, for the child was supposed to have been seized by supernatural flames which had been lit by the divine breath, and the attention of the 'terrible demons of vengeance' was not to be attracted. Terracotta masks, representing hideous, grimacing demons, have been found in the tombs, and as they had been dedicated to the god of the topheth, it seems likely that they were copies of the ones worn by the dancers during the moloch ceremonies.
On the other hand, Serge Lancel cites a more sober (and probably more realistic) reconstruction of the affair:
On the area of the tophet, or in its immediate proximity, a small pyre of intermingled resinous branches is erected in the open air... A baby or very young child (more rarely two) is laid on its back directly touching the branches, or perhaps separated from them by a piece of wickerwork. The child is clothed or wrapped in a cloth held together by two fasteners. There is nothing to indicate whether it is alive or dead, but in the first eventuality its limbs are doubtless bound since it does not change its position. The pyre is set alight. Before the process of cremation gets under way, sometimes only afterwards, part or the whole of a newborn animal is placed alongside the infant. The first is not poked but fanned to ensure complete combustion. When the calcination is deemed sufficient, a handful of earth or sand is used to extinguish it.... The moment comes to fill the urns. Ashes and embers are, if necessary, cooled down with water and, after the maximum amount of fuel has been removed, they are tipped from the pyre's support into the urn. Bones that are too long may be broken if the need arises; following which, a few jewels, chiefly bead necklaces and amulets, are spread on the surface of the ashes, then the urn is closed with an inverted piece of pottery or a plug of clay.
Not everything was so morbid, of course. Centuries after the fall of Carthage in 146, the local population continued to worship Baal Hammon or his Roman equivalent Saturn. Although the evidence is quite limited, in Punic eschatology Baal Hammon might have been a psychopomp who led souls into the afterlife.
Three other Baals deserve some attention: Hadad/Baal Shamin (b‘l šmn), Kushor/Baal Malage (Phoenician name unknown; possibly b‘l mlk’?), and Baal Saphon (b‘l ṣpn). They are invoked as Ares, Triton, and Poseidon, respectively, in the Greek translation of the treaty between Hannibal and Philip V of Macedon in 216 (the Punic original is lost), which itself follows a Tyrian treaty tradition. In their Canaanite-Phoenician-Punic context, all three gods are associated with the sea or storms. We unfortunately don't know much about their role in Phoenician-Punic religion.
Numerous other Baals appear in dedications and inscriptions. The most curious among these is probably Baal Magonim (b‘l mgnm), mentioned in a single Carthaginian text. Scholars have puzzled over its meaning; some even suggesting that it refers to the so-called "Magonid" dynasty of the fifth century (thus "Baal of the Magonids"). A more plausible interpretation is something like "Baal of the Shields." But as you can probably tell by now, little is known about many of these deities besides their names and the fact that people worshiped them. I'm sorry if doesn't quite answer your question, but I hope you find it informative nonetheless! :)
Further reading:
Barré, Michael L. The God-list in the Treaty Between Hannibal and Philip V of Macedonia: A Study in Light of the Ancient Near Eastern Treaty Tradition.
Huss, Werner. Die Karthager. Munich: Verlag C. H. Beck, 2004.
Lancel, Serge. Carthage: A History. Translated by Antonia Neville. Oxford and Cambridge: Blackwell, 1995.
Smith, P., G. Avishai, J. A. Greene, and L. E. Stager. "Aging cremated infants: the problem of sacrifice at the Tophet of Carthage." Antiquity 85 (2011): 859-74.
Wasn't that more common in worship of Marduk than Baal?