Certain compounds exhibit a decrease in solubility as temperature increases, and these are typically salt-like compounds or those with strong lattice energy that is not overcome by increased thermal energy. A classic example is calcium sulfate (CaSO₄).
Calcium sulfate, among other similar salts, tends to have lower solubility at higher temperatures, meaning it would exhibit lower solubility at 50°C compared to its solubility at 20°C. This behavior can be attributed to the energetics of the dissolution process, where the lattice energy of the solid is not sufficiently overcome by the enthalpic gains from solvation at higher temperatures.
So, if you are looking for a specific example, calcium sulfate is a good choice of a compound that exhibits lower solubility at elevated temperatures compared to lower temperatures.