I used to make fudge lots when I was younger with no probs. But last night when I tried, it burnt really badly on the bottom before it had reached the right temperature on the thermometer. So I ended up taking it off the heat before it was ready, and have ended up with a weird tasting not-quite-right textured substance (obviously I'm still eating it, it's made of sugar, butter and milk?).
What did I do wrong? Wrong sort of pan maybe? It's a fairly heavy-bottomed one.