Melt butter in a sauce pan, stir in brown sugar, corn syrup, and salt. Bring to a boil, stirring constantly.
Next boil without stirring for five minutes. Remove from heat, stir in vanilla and soda.
Pour over freshly popped popcorn, immediately mix well.
Dump into a 9 by 13 inch cake pan and bake at 225 for one hour, stirring every 15 minutes.
Remove from oven and dump onto a cookie sheet or flat container
. Immediately spread out caramel corn to prevent it from sticking together.
Cool completely and put in an air tight container. Enjoy!!