What is fractional crystallization?

Question

That's all I need.
Any detailed answers on it? and how/why it occurs?

Thanks

Answer 1

Crystallization in which the early-formed crystals are prevented from equilibrating with the liquid from which they grew, resulting in a series of residual liquids of more extreme compositions than would have resulted from equilibrium crystallization.

Controlled precipitation from a saline solution of salts of different
solubilities, as affected by varying temperatures or by the resence of other salts in solution.

Is a process to separate different solvents from a solution.

Answer 2

Here's a useful link...