Pop the popcorn according to package instructions and place it in a large bowl.
In a saucepan, combine sugar, corn syrup, butter, and salt.
Cook over medium heat, stirring constantly until the mixture boils.
Once boiling, stop stirring and let it boil for 2 minutes.
Remove from heat and stir in vanilla extract.
Pour the syrup mixture over the popcorn and mix until coated.
Allow the mixture to cool slightly, then grease your hands with butter.
Form the popcorn into balls and place them on parchment paper.
Melt chocolate chips and drizzle over the popcorn balls if desired.
Let the popcorn balls set before serving.