Heat sugar, liquid and butter until slightly thickened. (5-6 minutes after coming to a boil). Cool completely. Add coconut after cooling. Beat egg whites until stiff. Mix thoroughly with coconut mixture. Return to heat. Cook 3 - 4 minutes after it begins to blurp over medium heat. Stir frequently. Stir in the vanilla. Ladle over 3 cake layers while the icing is still hot.