2. Boil fudge mixture. In a medium saucepan, set over medium heat, stir together the sugar, butter, salt and evaporated milk together. Bring mixture to a boil (it can take up to 10 minutes to bring to a boil) , and then let the mixture boil until it reaches a temperature of 234°F (this usually takes about 3-5 minutes). If it goes beyond 234°F I found the fudge to be a bit gritty and sugar has crystallized.