In a medium saucepan, combine sugar, corn syrup, water, cocoa powder, and salt. Cook over medium heat without stirring until the mixture reaches the soft-crack stage (approximately 270°F).
Remove from heat and stir in red food coloring, butter, and vanilla until smooth.
Pop the popcorn using an air popper, discarding unpopped kernels.
Spread popped popcorn on a baking sheet. Drizzle caramel over the popcorn and toss gently to coat evenly.
Allow to cool completely before breaking apart clumps.
Optionally drizzle melted white chocolate over the cooled popcorn.