When your soldier is killed by a shot from far away, he gurgles and keels over before the shot actually hits him. In this specific case, I've observed hovernet shots do this, but I'm pretty sure it could be any kind of shot.
Attached is a savegame with a Hydroelectric Dam mission, where this effect shouldn't be hard to reproduce - just line most of the soldiers up near the fence and wait for enemies at the far end to snipe them.
