Technically a bomb is any high pressure expansion. The most common type is created by combustion.
Rupturing a pressurized fuel source and providing ignition at the same time is your typical trope. The typical trope is to shoot the gas tank, but we all know that doesn't work by itself without an ignition source.
The same technique of explosive ignition is also the standard method of amplifying a tiny intense explosion into a huge show-worthy distracting fireball. Using a small amount of stable explosives and a tank full of gasoline, Kerosene, or Diesel (depending on the desired explosion effect) is the standard method to make a Hollywood explosion.
Conventional old style explosives are made from carbon, sulfur, phosphorus, nitrogen and oxygen. Charcoal and Sulfur-Nitrate (in the form of Sulfur Ore) are the primary source of old-style handmade Black Powder.
Plant Cellulose combined with a straight Nitrates with a balance of Phosphorus and Sulfur as stabilizing agents is used for Smokeless Gunpowder. Ironically what is now used as smokeless gunpowder was initially found in old 1920s film. Hence why old is so dangerously explosive.
However, any element that reacts with oxygen can be made explosive, and nitrogen has several compounds (Nitrate and Nitros compounds) that ocure in both minerals and organic matter that make this easy.
A small amount of two metal oxides, typically iron oxide and aluminum oxide, either heated to a very high temperature, or mixed with several other compounds that I recommend you just vaguely call "several other compounds" because how dangerous this stuff is, can be used to create thermite, which is a slow burning but insanely hot compound. This could also be used as a distraction, particularly when destroying something.
Furthermore, any compressed gas chamber is also subject to a form of explosion of sudden release. For instance a shooting a bottle of hair spray has been used to create a small explosion in many a movie. Although most bottles have better safety design now to prevent such an explosion, we can give artistic liberty that such safety considerations go out the window in your typical sci-fi dystopia. In fact, it would be artistic liberty to say companies wouldn't cheap out on safety in a sci-fi dystopia.
Seriously, I thought this was all common knowledge.