Preheat oven to 300 degrees. Line a baking sheet with parchment paper. Coat the inside of a large bowl with cooking spray, and add popcorn to the bowl.
In a medium pot over medium high heat, combine the sugar and water, stirring constantly until sugar dissolves*. Continue to cook, swirling occasionally, until sugar-water mixture is amber in color, about 10 minutes.
Remove pot from heat and stir in the soy sauce, butter, and sesame oil** (there will be a lot of bubbling). Once all butter is melted in, return pot to heat and bring back to a boil. Cook for an additional 2 minutes.
Remove pot from heat once again and stir in the baking soda and ground ginger. As soon as everything is evenly mixed, quickly pour mixture over the popcorn and toss to coat.
Spread coated popcorn out on your parchment-lined baking sheet and bake at 300 degrees for 20 minutes, tossing once halfway through baking***.
Remove popcorn from oven, and allow to cool slightly before serving. Once cooled, popcorn can be stored in an airtight container for several days.
***When the popcorn comes out of the oven, the caramel may still seem a little sticky - this is normal! It will become hard and shiny as soon as it has a chance to cool a bit. The finished product will be edible by the handful without leaving any sticky caramel residue behind!