In recipes that call for a specific amount of boiling water, how much does it matter when you measure the water?
We baked two batches of Devil’s Food Cake, one using 1 cup of cold water heated to boiling and one in which we boiled a small pot of water, then measured out 1 cup. The cake made with the measured-then-boiled water baked up 1/4 inch shorter and noticeably less moist than the cake made with water measured after boiling. We found that even in the short amount of time that it takes to boil 1 cup of water, nearly an ounce, on average, is lost to evaporation. So for the best results, boil before you measure.