In Ottoman Turkey, the turban was so intrinsically linked to social class and status that they were incorporated into gravestones in ever more elaborate configurations - [this site] (http://www.turkeygravestones.com/professions.html) has a fascinatingly dense gallery of them arranged by religious sect and caste. Turban size became a minor obsession, with Suleiman's being particularly legendary in stature.
To underline the significance placed on turban size, laws on clothing passed in the Suleiman era decreed that no turban could exceed the height of the Sultan's.
Suleiman the Magnificent by André Clot describes Suleiman as wearing "a tall turban surmounted by a spray of diamonds and precious stones" while other sources go further in describing a large, round turban wrapped around a cone-like frame which projected from the top into a neat point - which fits with the picture you've linked to.
That cone was probably what kept it in place and kept it in shape.
Sources: Consumption Studies and the History of the Ottoman Empire, 1550-1922 by Donald Quataert and Suleiman the Magnificent by André Clot
As a follow on question, did it have any particular significance with regards to foreign countries (e.g. "My hat's bigger than his because I'm a better ruler")?
