Jell

To become a jelly. Early examples are hard to find; but Mr. Fitzedward Hall remembers the word, 1830–40. (N.E.D.)

1874.  She reboiled, resugared, and restrained, but the dreadful stuff wouldn’t ‘jell.’—Louisa M. Alcott, ‘Good Wives,’ chap. v. (N.E.D.) (Italics in the original.)