Oops!
Numerous accidents during experiments with your bombs made you resistant to their explosions.
Prerequisites: Alchemist's Bomb class feature.
Benefit: You are immune to your own bomb's damage and special effects.
Short Fuse
You've concocted a new formula for your bombs which makes them much more explosive, but also less stable and prone to explode quicker.
Prerequisites: Alchemist's Bomb class feature, Oops! feat.
Benefit: You can make improved bombs that increase their damage to d10 instead of d6 on direct hit and 2 instead of 1 per bomb HD on splash, but decrease their range to 10 feet and they explode in your adjacent square if you roll a 1 on your attack roll.
Alternatively those can be discoveries.