Combine sugar, corn syrup, and butter in a large, heavy saucepan over medium heat. Cook 18 minutes or until a candy thermometer registers 275°, stirring frequently. Add peanuts; cook 3 minutes or until a candy thermometer registers 295°, stirring constantly. Remove from heat; stir in baking soda and chile powder. (The baking soda will cause it to bubble and become opaque.)