Atomize* some propelant, boom, explosive.
The trick is to get the atomized propelant to "boom, explosive" at the target and not in your backpack.
Also, you probably want a "boom" sufficient to accomplish whatever demolition you're planning, which - again - raises the stakes regarding what's in your backpack.
There's a classic little film called "The Wages of Fear" that explores the hazards of amateurs transporting high explosives over long distances.