21.   Bring to a boil, stirring until sugar dissolves.

22.   Bring to a simmer, and cook, stirring, until sugar dissolves.

23.   Bring to boil, stirring until sugar dissolves.

24.   Bring to a simmer over moderate heat, stirring until the sugar dissolves.

25.   Bring to a boil and cook, uncovered, stirring occasionally, until the sugar dissolves.

26.   Bring to a boil and stir until the sugar has dissolved completely.

27.   Bring to a boil, stirring occasionally until sugar dissolves.

28.   Bring to a boil, stirring until the sugar dissolves.

29.   Bring to boil, reduce heat to low, and simmer, stirring, until sugar dissolves.

30.   Bring mixture to a boil and stir until sugar dissolves completely.