gelatinize

The starch may not have fully gelatinized during this time, but it will have absorbed and retained moisture that would’ve been lost to the heat, keeping the texture smooth.

It will seize into a lumpy mess because the outside of the cornstarch clumps will gelatinize, while the insides will stay dry.

Though the solution does not gelatinize, it preserves the property of gluing surfaces together when it dries.