FTC Water Rocket Explodes

Over the week I have been building a FTC water rocket. It has a 3L capacity and *should* be able to withstand 150 psi. So we pressurized it to 150 psi. But just 2 seconds before my dad pulls that almighty string that launches the rocket, BOOM! Then it was gone... I couldn't Beleave how loud it was. You could hear it echo from the trees around us. Personally I was expecting one of the bulkheads to give way than the pressure chamber it's self. It was awesome!