In large, buttered bowl, mix popcorn and coconut. In saucepan, combine sugar, syrup, butter, water and salt. Bring to boil over low heat, stirring until sugar dissolves. Continue cooking until syrup reaches hard crack stage (290-295 degrees).
Stir in vanilla. Pour syrup in fine stream over popcorn mixture; stir until particles are evenly coated with syrup.
On buttered, 12-inch pizza pan, spread half of popcorn mixture in thin layer, covering bottom of pan. Mark off into 12 wedge-shaped servings; set aside. Repeat using remaining popcorn mixture; cool.
Cover one layer with ice cream; top with second popcorn layer. Store in freezer. To serve, cut in wedges. Serve with fruit or chocolate sauce, if desired.