Here's why:

* Dissolving is an endothermic process: This means it requires energy (usually heat) to break the bonds holding the salt ions together in the solid state and to separate them into individual ions in solution.

* Le Chatelier's Principle: When you increase the temperature, you're adding heat to the system. The system will shift to relieve that stress, which in this case means favoring the endothermic process of dissolving more salt.

Exceptions:

* Some salts exhibit unusual solubility behavior: For example, the solubility of calcium sulfate (CaSO₄) decreases with increasing temperature. This is because the dissolution of calcium sulfate is an exothermic process, and adding heat actually shifts the equilibrium towards the formation of solid calcium sulfate.

Key point: While the general rule is that salt solubility increases with temperature, it's always a good idea to check specific solubility curves for individual salts.