Final answer:
Whipping egg whites causes the proteins to undergo denaturation, resulting in coagulation.
Step-by-step explanation:
When egg whites are whipped, the proteins undergo denaturation. Denaturation is a change in the three-dimensional structure of a protein that renders it incapable of performing its assigned function. Heating causes the protein structures to unfold and expose hydrophobic groups, which then aggregate and cause the proteins to coagulate.