Lightly grease and flour a 10 cup bundt pan. In large mixing bowl, combine cake mix and pudding mix. Add soda, oil and eggs. Beat at medium speed until smooth. Pour batter into prepared pan and bake for 45-50 minutes, or until a wooden pick inserted in center comes out clean. Let cool in pan for 10 minutes. Remove from pan and let cool.Mountain Dew Cake Glaze: 1 stick butter, 1 cup sugar, ½ cup Mountain Dew. Mix together and boil for 2 minutes. Pour glaze over cake, let cool. Turn out on to platter.