Here's why:

* For most solids dissolved in liquids: Increasing the temperature increases the solubility. This is because the added energy from heat helps break the bonds holding the solute together, allowing it to better interact with the solvent molecules.

* For gases dissolved in liquids: Increasing the temperature decreases the solubility. This is because the gas molecules gain kinetic energy and escape from the solution more easily.

Exceptions:

* Some salts: There are exceptions to the general rule. For example, the solubility of some salts, like lithium sulfate (Li₂SO₄), actually decreases with increasing temperature.

In summary:

* Temperature is a key factor influencing solubility.

* For most solids, higher temperature means higher solubility.

* For gases, higher temperature means lower solubility.

* There are exceptions to the general rule.

It's important to remember that solubility is a complex phenomenon, and there are many factors that can influence it, including the specific solute and solvent, pressure, and the presence of other solutes.