Amaretto Simple Syrup

In a small saucepan, combine 1/2 cup water and the sugar over medium-high heat. Cook, stirring, until sugar has dissolved. Stop stirring, and bring to a boil; reduce to a simmer, and cook until mixture has thickened slightly, about 5 minutes. Remove from heat, and stir in almond liqueur. Cool syrup to room temperature before using. The syrup can be refrigerated in an airtight container, up to 1 month.