In a medium saucepan, add the sugar and corn syrup. Over medium heat, stirring often, bring the mixture to a steady boil.
Remove from the heat and stir in the peanut butter, vanilla, and salt until smooth. Immediately pour the warm mixture over the popcorn. Toss until the popcorn is evenly coated.
Popcorn: 1/4 cup unpopped corn kernels equals about 7-8 cups popped popcorn.Gooey Factor: If you want more caramel to popcorn ratio (or vice versa), you can adjust the recipe as needed, increasing the peanut butter caramel ingredients or adding more or less popcorn.