Bomb Boosts are used for several large sequence breaks. There are 2 main ways that they are performed.
If you roll into a bomb as it starts it's 4th quick red flash, you can gain a significant amount of distance.
This is not often used as the distance you can launch is not very large. It is used in Sand Temple for the Boss Key Skip as it gives like more distance when launching off the block.
Jumpslash bomb boosts are the only way for link to cross gaps that are 3 tiles large. To perform this you need to wait for the 4th quick flash of the bomb and jumpslash an enemy.
This is used to reach the boss key in Ocean Temple early as well as skipping the left side of the big room in Tower of Spirit 4.