I mixed my cornstarch and water in a bowl, then poured into my crockpot with my soup.
It foamed up and boiled over before I was able to put my bowl and spoon down to grab
I know some folks who add cheese to thicken it.....but that only is if you like cheese in your soup???
I have never heard of cornstarch foaming. And your crockpot must have been on full boil. It should have worked, I do not know why this would have happened.
© RDA Enthusiast Brands, LLC 2014