Popcorn Balls

In a medium saucepan, mix all ingredients except the vanilla. Cook, stirring occasionally until mixture reaches 270 degrees F, or brittle ball. Take off heat and stir in vanilla. Pour over the popcorn, and stir lightly and quickly to coat. Shape quickly with butter coated hands (it's important to coat hands with butter or some kind of oil to keep the hot syrup from sticking to your skin). Note: If desired, food coloring can be added before cooking.