Put sugar and water in a medium saucepan and bring to a boil over medium heat.
Simmer, stirring until the mixture begins to turn a caramel color, about 10 minutes.
Toward the end of the cooking, the mixture will become very foamy as it starts to
darken. Stir constantly at this point and, just as it becomes a medium caramel color,
turn off the heat but continue to stir. It will become darker off the heat.
coffee, being careful since the mixture tends to spatter when the coffee first makes
contact. Mix well and let cool.