Grand Marnier Syrup

In a small saucepan with a tight-fitting lid, bring the sugar and water to a rolling boil, stirring constantly. Cover immediately, remove it from the heat, and cool completely. Transfer the syrup to a glass measure and stir in the Grand Marnier. If the syrup has evaporated slightly, add enough water to equal 1 cup plus 2 tablespoons of syrup. Cover tightly to prevent evaporation. The syrup keep