About 20 years ago, I was a deacon at a church where the youth pastor would cook a large meal at every youth meeting (30 kids for a whole afternoon). One day, he was very busy and left a recipe for some of the kids who cook at picnics, but instead of adding the alcohol BEFORE cooking (for the fruity taste), they added it AFTER COOKING. That was the day 30 kids and helpers got drunk (they probably simply went to sleep).
Yes, the heat boils off the intoxicating alcohol, but I never heard of the simple addition of boiling water.