Introduction to supersaturated solutions
A supersaturated solution refers to a solution at a certain temperature and pressure when the concentration of the solute in the solution has exceeded the solubility of the solute at the temperature and pressure, but the solute has not yet precipitated. This phenomenon is called oversaturation. Supersaturated solutions are unstable. If the solution is stirred, the solution is shaken, the container wall is rubbed, or a solid "seed" is put into the solution, the excess solute in the solution will immediately crystallize out.