I made some chocolate mousse for a cake today, which I had made successfully in the past. However, this time, I experienced a totally unexpected problem. The recipe tells you to boil about 1/2 cup sugar with three TBSP of water to 257 degrees F, and then to whisk it into an egg/egg yolk mixture. However, every time I did this, the syrup turned almost instantaneously into hard rock! Soem of the syrup seemed to get integrated properly into the egg, but there were these big rocks. I did it over three times, even using a different thermometer, and all three times created the same big hard rock in the egg mixture. I cannot figure out what went wrong. I measured exactly. What could be the cause?