In 1978, Random House recalled the Woman’s Day Crockery Cuisine cookbook because one of the recipes could apparently “cause a serious explosion.” According to a statement from Random House, “If the recipe (for Silky Caramel Slices) is followed, the condensed milk can could explode and shatter the lid and liner of the crockery cooker.” (Please, no Boston Marathon bomb jokes.) From a May 1978 article in the Chicago Tribune:
Because of an unfortunately elusive line that should have instructed folks to fill the pot with water, following the recipe appears to have resulted in some unintentional pop-top cans and badly damaged crockpots…
The conditions that have made this underground recipe successful and therefore popular, especially with children, are water and temperature. By being heated in boiling water, the temperature of the can and milk do not exceed the boiling point. After a few hours of this, the sugared milk turns to a caramel pudding. In the Crockpot, however, especially without water, the temperature can build up rather like a pressure cooker. That was the most immediate cause of the problem.
“The Exploding Recipe” (Weird Universe)