In large saucepan, combine brown sugar, butter and corn syrup. Boil for 5 minutes,
then remove from the heat. Add baking soda, vanilla extract and salt. Stir thoroughly.
The mixture will "foam up." Pour over the popped corn and mix well.
Bake at 250 degrees F for 40 minutes. Stir every 15 minutes.
You may stir into the popcorn 1 can of mixed, salted nuts before pouring the
syrup over and baking.