A Bend in the River by V.S. Naipaul was one of those books on the list where it is a novel, but it is also intended to teach something. It wasn't heavy handed or annoying though - I really was interested to read the story set in a post-colonial African city. I knew nothing at all about this topic before beginning the book. The main character is not from the city and goes there to set up a little shop and witnesses all the changes and troubles that people have there. The main character is not necessarily likeable (I'm mainly referring to the fact that he beats up a woman at one point).
Another interesting point is that his family (who lives on the coast of Africa) had slaves dating from a long time ago but it has become way different from US pre-Civil War slavery. The tables have kind of turned on his family and they can't do anything about the slaves. The slaves (which have now multiplied and become numerous) are entitled to the family's care and support.
This was generally pretty interesting, if a little slow at times.