In candy making, or the first step in making a caramel sauce, you start by boiling sugar and water together until golden brown. Sounds simple, hard to imagine anything can go wrong. But if what happened in the picture below has happened to you, this will explain why it happened, and let you know what you can do so it won't happen again.
Candy making recipes or caramel sauce recipes usually start by combing a large amount of granulated sugar with a small amount of water. Because sugar melts into a liquid once it's heated past a certain temperature, the mixture can completely liquefy and begin to boil.
Boiling further concentrates the sugar by evaporating the water out, and eventually the mixture browns into a lovely golden color - although heated too long and it can quickly burn causing the mixture to be ruined.
There are 2 important points to remember during this initial boiling stage (when it's just water and sugar):
1. Once the sugar has dissolved and the mixture beings to boil, do not stir.
If the sugar still hasn't completely dissolved, swirl the pan gently only. Once everything is dissolved you don't need to swirl the pan at all, let it boil undisturbed.
2. Any sugar crystals the form/stick to the sides of the pan while the mixture is boiling must be dissolved using a pastry brush that has been dipped in water.
Do this the entire time the sugar/water solution is boiling.
Sugar is a crystal and crystals like to stay in formation. Because of this property, once this super-saturated sugar solution is liquefied, all it takes is one 'seed' (ie. grain of sugar) to cause the entire mixture to precipitate and re-crystallize back to its original state.
The process of stirring causes the sugar to clump briefly out of solution, which can lead to re-crystallization. As well, any sugar crystals that are stuck to the sides of the pan that fall into the boiling mixture can also trigger this re-crystallization and 'seize' the entire mixture - making it unusable. If this occurs, like in the picture below, the entire mixture must be thrown out and you have to start from scratch again.
Once the mixture has reached a certain temperature and you add other ingredients depending on what you're making (like butter or cream for toffee or a caramel sauce), at that point it is fine to start stirring the mixture. The addition of other ingredients reduces the concentration of sugar and prevents the mixture from seizing.