The solubility of a certain substance does not change with temperature. How can you make an unsaturated solution of such substance saturated?

Explanation

As unsaturated solution contains lesser amount of solute than its maximum capacity on subjecting the solution to evaporation, some amount of water vaporizes. Since lesser amount of water is present in the solution and the amount of solute is same, the solution at some stage may become saturated as the solubility of the substance remains same even on heating.