This question already has an answer here:

I have mostly come across examples of solids whose solubility increases in liquids with an increase in temperature. However, there seem to be exceptions to generalized rule this such as the solubility of $\ce{Ce2(SO4)3}$ in water. What makes this substance so special?


marked as duplicate by Mithoron, Mathew Mahindaratne, Karl, Todd Minehardt, Tyberius Aug 12 at 17:09

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.