The use of a salt solution containing excess of salt to cause vomiting has been in practice since a very long time. Salt has a water
retention property. When a solution containing excess of salt is taken, then due to osmosis water will move into the intestine,
putting pressure on the intestinal walls. This also causes nausea. The intestinal wall is not able to tolerate this strain, and hence
this excess water retention causes vomiting.
Thus we can say that the phenomena responsible for vomiting after taking a concentrated salt solution is osmosis.