1. Preheat oven to 325 degrees F (165 degrees C). Liberally grease (either way cooking spray or butter) a bundt pan, and then pour sugar into it and swirl around until the entire inside of the pan is coated in sugar. (Discard any remaining sugar.)
2. In a large bowl, combine cake mix and pudding mix. Mix in the eggs, 1/2 cup water, oil and 1/2 cup rum. Blend well. Pour batter into pan.
3. Bake in the preheated oven for 60 minutes, or until a toothpick inserted into the cake comes out clean. Let sit for 10 minutes in the pan, then turn out onto serving plate. Spoon glaze over top and sides. Allow cake to absorb glaze and repeat until all glaze is used.

Glaze Instructions:

1. In a saucepan, combine butter, 1/4 cup water and 1 cup sugar. Bring to a boil over medium heat and continue to boil for 5 minutes, stirring constantly. Remove from heat and stir in 1/4 cup rum.