Maybe stacking behaviors over time? They could be given a death effect. You'd need to test to see if it works... and I imagine it could potentially be a laggy solution...
You could potentially do something with like 5 behaviors and five damage effects (100, 200, 300, etc), one for each behavior. When a behavior expires, it gives the bomb the new behavior, with the increased damage.
I created a demo map to demonstrate how this can be achieved with Accumulators. Basically what it does is calculating the fraction of time compared to the full duration and using the Application Rule: Multiply to multiply this with the amount the Accumulator is assigned to, in this case the effect damage.
This also means that after 0.1 sec it deals 10 damage. Or even with a higher precision, as this is what Accumulators are designed for. I hope this is not an unwanted behavior, otherwise you could use an Accumulator with Stack Count to get a more partitioned effect.