Other solutions involving gaseous solutes in water will release thermal energy during the solution formation process. These solutions are said to have an exothermic Heat of Solution. Unsaturated solutions are those that are below the solubility limits of the solute in that solvent. Saturated solutions are those that are at the solubility limits. Supersaturated solutions are those solutions that are above the solubility limits.
Supersaturated solutions are meta stable.
Such solutions will have the excess solute crystalize out with any disturbance of the supersaturated solution. Providing a tiny crystal of the solute or scratching the sides of the container which introduce micro chips of glass into the supersaturated solution so the excess solute can crystalize upon its surface, will illicit the dramatic crystallization of the excess solute out of the solution restablishing a saturated solution. The solubility of a particular solute in a solvent is the maximum amount of solute that will dissolve in a specified amount of solution or solvent. It represents the saturated level of the solution where no more solute will dissolve within the solution. When the rate of the forward process is equal to the rate of the reverse process, then the system is said to be in a dynamic equilibrium.