Another recipe from my mom, I think this might be similar to what some people call Sea Foam Candy - it's very light and porous.

1 cup sugar
1 cup dark Karo syrup
1 Tablespoon vinegar
1 Tablespoon baking soda

Cook sugar, syrup and vinegar in large pan over medium heat. Stir only until sugar dissolves. Cook to 300 F. or until a drop in cold water is brittle.

Remove from heat, stir soda in quickly, mixing well. Pour into buttered pan. It should be very light and porous and harden quickly.

(Nora Estrem)