Halloween. Combine sugar, corn syrup, water, and salt in a saucepan; cook over low heat, stirring gently, until sugar dissolves. Cook over medium heat, without stirring, to hard ball stage (254 degrees). Remove from heat, and stir in butter and vanilla.Place popped corn in a large pan. Pour hot syrup over top, stirring well with a wooden spoon. Grease hands with butter, and shape mixture into balls. Place on wax paper to dry. Wrap in plastic wrap, and store in a cool, dry place. Yield: about 2 dozen.