Why should not the solvent completely evaporate in the recrystallization method of purification?

In the recrystallization method, the solvent should not completely evaporate because residual solvent is necessary to maintain the solubility of the solute in the solution. If the solvent evaporates entirely, the solute may precipitate out prematurely, leading to impurities being trapped in the solid or causing incomplete crystallization. Maintaining some solvent allows for a better-controlled crystallization process, ultimately resulting in purer and more uniform crystals.