Given a clear solution of KNO3, I would say that the solution is unsaturated. This type of solution has a solute concentration that is lower than the equilibrium solubility of the solute in the solvent. It is characterized by having a homogeneous solution, there would be no solid particles in the solution. Solubility is the measure of how much of a solute can be dissolved in the solution without forming any precipitate or solid particles. Any concentration above it would cause for the solute to precipitate out from the solution. To test whether the solution is unsaturated or saturated, you can add more of the KNO3 solute, if the resulting solution would still be clear then it is an unsaturated solution. However, if precipitate would appear then the original solution is saturated.
