I decided to try my hand at peanut brittle today and results have been less than stellar. I'm a bit baffled why. I started with 1/2C water, 1C sugar over medium heat. My understanding is that hard crack happens at 300-310F, so that was my target temperature. At 275F, the whole thing seized into a powdery mess. Applying further heat gradually turned the powder to a brown, carmel-y substance. My analysis of what happened: I overshot the target temperature. At some point past 310F, every last bit of water was gone, resulting in the powdery mess. The further heat just melted this remaining sugar into a carmel. Conclusion: I need a new candy thermometer. I grabbed a different thermometer and started again. At 275F, the exact same thing happened. Two thermometers being off by an identical amount seems like an incredible coincidence - hence, I'm pretty confused. Is my analysis reasonable? Ideas what I should be doing differently?