Dry ice in a 2 liter plastic bottle will exceed the bursting pressure of the bottle, and the bottle explodes with a loud “boom.” Not particularly dangeorus.
As I see it, it could work in a glass bottle that wasn’t strong enough to contain the pressure of the C02 as the solid changed into a gas. That would depend on how much dry ice was used, the size and strength of the container, and the ambient temperature.
“What, pray tell, is a dry ice bomb and what is it supposed to do? I can see dry ice being used as, say, a detonator. But I can’t see it generating a very powerful explosion in and of itself.”
When dry Ice sublimates in a confined space the pressure of the gas can exceed 1000 psi at room temperature. If it’s a plastic bottle the bottle will fail at a much lower pressure but if it were in a metal container it could be very dangerous.