The solubility of a solute is the maximum quantity of the solute that will dissolve in a given quantity of solvent for a particular temperature and pressure. A change in temperature and pressure alters the solubility of solutes differently based on their phase.
The solubility of solids is usually observed to increase as the temperature rises; the solubility of gases decreases with a rise in temperature; and for liquids there is a very small effect.
This variation for the three phases can be explained by looking at the reason behind the change. Before solutes can dissolve, the bonds that hold the particles together have to be broken. In the case of solids, the bonds are quite strong and it requires a relatively large amount of energy to break the bonds. This is facilitated by an increase in temperature. In the case of gases, the energy with the solute particles increases with an increase in temperature that actually reduces solubility.
In the case of liquids, the bonding energy between particles that make up the solute is very small. A change in temperature has very little effect on the ease with which the bonds break up. On the other hand, a higher temperature does not significantly increase the rate at which the particles move about. This makes the solubility of liquids vary by a very small extent with a change in temperature.