Are there any Explosives (Bomb materials) that don't naturally leave a chemical/forensic trace?
What's the trace of a lithium ion based explosive (mobile phone device) inside a compact non-security screened food container.
For chemical-based explosives, let's just say that there are fingerprints for everything if you know what to look for and have the cash to do so - noting that if there weren't, this would not be the place to say.
In common use, there are nitrates or peroxides, both of which can be picked up in various ways.
Lithium ion devices are not explosives in the true sense; they have thermal effects (thermal runaway).