How is crystallization an example of self-assembly?

Crystallization is a solid-liquid separation in which the solid crystals form from the cooled solution. This is a tecnnique used by chemists to purify solid compounds. It is based on the principle of solubility wherein solutes tend to be more soluble in hot liquid solvents than they are in cooler solution. So how is this considered a self-assembly? Consider a salt dissolved in a hot solution. Continue adding salt to the hot solution until no more salt can be added. Now add one teaspoon of salt. The salt that does not dissolve is the first step of crystallization.