This is what I remember from my undergrad Scandinavian History course. Forgive me if it is not detailed enough.

Norway used to have a very vibrant nobility, however, in 1821 Norway passed the Nobility Law which abolished all noble titles and privileges for all future generations. Current nobles and their living children were able to retain their titles but they could no longer be passed down. I believe the last noble died in the early 1900s. This was an outgrowth of the Norwegian Constitution which was passed a few years prior and prohibited the creation of any new noble titles.