I've tried to make flan a couple times recently. The recipe I have calls for 1 cup of white sugar and 1/4 cup water, put in a saucepan over med/low heat, stir occasionally until sugar melts then turns golden brown. Both times I've tried, the sugar melts and bubbles, and after about 20 minutes it kind of dries up and all crystalizes. If I add more water it will mostly disolve, but I can't get to the carmelization without having it crystalize again. What am I doing wrong?