1. Preheat oven to 250 degrees. Put popcorn in a large, deep buttered baking pan. Keep warm in the oven. (I usually don’t do this, but it’s a good idea)
2. Combine sugar, corn syrup, water, butter and salt in a large saucepan. Stir over medium heat until sugar is WELL dissolved.
3. Cook until mixture reaches 250 F on a candy thermometer, stirring frequently. ( I use the cold water method, and cook it until it reaches a soft ball stage). Remove from heat.
4. Quickly stir in the vanilla.
5. Remove popcorn from the oven. Pour syrup mixture over the popcorn, stirring to mix well. Grease your fingers with butter, and form into balls. Place on wax paper to cool. Make sure the balls are fully cooled & store in large Ziploc bags. They will stay chewy good, for a long time.