To congeal means to thicken, clot, cake or coagulate. Mary cut herself with a knife, but within a few minutes the blood started to congeal.

Yes. There is a way to safely congeal someone in jello.

How?

If you don't wash the dishes right away, the food on them will congeal over the warm night.

If you meant 'congeal' - one answer could be "the spilled soup dried, making it congeal into a dark stain."

To change into curd; to coagulate; as, rennet causes milk to curdle., To thicken; to congeal., To change into curd; to cause to coagulate., To congeal or thicken.