fruit salad

Oh, how I wish I'd paid attention! My mom told me of an easy way to make a dressing for fruit salad, using the juice from one of the fruits (using canned) or whatever fruit juice you may have on hand. You bring it to a boil on the stove...Anyways, I don't remember exactly how to do it--does anyone use this technique? I have strawberries, raspberries, apples, oranges, watermelon, grapes and canned pineapple just dying to be made into a salad! Thanks in advance.