Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13 inch baking dish.
Beat together cake mix, water, egg whites, and oil in a large bowl with an electric mixer on low speed until moistened, about 30 seconds. Increase speed to medium and continue beating until well combined, about 2 minutes. Pour batter into the prepared baking dish.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, 23 to 28 minutes.
Remove cake from the oven. Poke holes in cake with a wooden skewer or toothpick.
Combine boiling water and strawberry gelatin in a medium bowl; stir until dissolved, then cool slightly. Stir in soda. Pour slowly over cake, allowing it to soak in. Refrigerate until cake is cool.
Make frosting: Combine milk and pudding mix in a medium bowl; beat until well blended and thickened. Fold in thawed whipped topping until combined.
Spread frosting over cooled cake. Refrigerate for at least 4 hours before serving.
Soda Pop Cake · Dinner Match Lab | Dinner Match Lab