This should come as you progress through the game naturally tho i will list some levels i found useful to quickly grind this one
This has to be done in a level, so the bubbles in the credits/menus do NOT count (i spent a long time popping the credits bubbles to no avail!)
The achievement unlocked for me shortly after "Pig Popper - Pop 1000 pigs"
After i had completed the game once i found these useful:
1-26: This early level has 9 bubbles that take little effort to pop with a few birds on the TNT boxes
E-7: This level has 16 bubbles which are all easily popped with 1 or 2 birds (this level is unlocked by hitting the golden egg in 4-16 its underneath the slingshot, hit it with your purple bird)
** please comment before neg voting, level suggestions will be credited if they are useful, Thanks SoS