like the blow torch principle. When metal gets super heated, the introduction of oxygen at high velocity is enought to cut through metal. When using an oxycetalene blow torch principle, the oxycetalene is just used to get things started. The oxycetalne is turned off and pure oxygen is used to cut through steel without the oxycetalene.
So retarding timing too much can super heat the exhaust side . The incoming fresh air at high velocity will induce the cutting principle and burn a hole. Keeping the boost up while this happens accelerates this. Makes sense to me.