In an effort to experimentally represent interstellar combustion, this video shows a quasi-detonating flame interacting with a reactive bubble to initiate a local deflagration-to-detonation transition (DDT) in an unconfined area. To do so, a spark plug ignites a hydrogen and air mixture which then produces a flame. After going through a series of turbulators, the flame accelerates until it reaches an unconfined box with a reactant bubble inside. By this point, the flame has produced its own shock and compression waves, setting the conditions for DDT. When the shock-flame finally interact with the bubble, just enough turbulence is created to spark the onset of DDT with the unconfined region.