What classes of fluids become more viscous when heated?

Certain non-Newtonian fluids, particularly those exhibiting shear-thinning behavior, can become more viscous when heated. An example is some polymer solutions, where increased temperature can lead to enhanced molecular interactions that increase the effective viscosity. Additionally, certain colloidal suspensions can also show increased viscosity with heat due to changes in particle interactions or aggregation. However, most fluids, especially Newtonian ones, typically decrease in viscosity with increased temperature.