As we know, when the memory becomes low, Android may start to kill some background apps to free memory. E.g. Nexus 7, this low-memory threshold is 64MB.
However, I observed that, even the available memory was enough (e.g. 150MB) to launch a new app (e.g. AngryBirds with 30MB), still the Android might kill some background apps. Is this possible?
If so, then what are the other "conditions" in which the Android "killer" would be also invoked?