The Last Three Plagues
Parshat Bo gives a description of the last three of the Ten Plagues. These were locusts, darkness, and the death of the first born sons.
The Alshich explained that each subsequent plague, was designed to elevate the Jewish people, and prepare them for the Revelation on Mount Sinai.
The locusts brought utter devastation to anything that grew in Egypt. The hand of G-d was seen by this devastating plague.
The darkness that was witnessed was unlike anything ever seen. It was also meant to weed out the four fifths of the Jewish people who were not worthy of leaving Egypt. They were killed during this plague so that the Egyptians would not see.
The killing of the first born was accompanied with the observance of the very first Seder in Egypt. The Angel of Death was unable to discern between the righteous and the wicked. Therefore, the Jews were asked to paint their doorposts with the blood of the lamb, that was offered as the Korban Pesach.
Jews were involved with circumcision and the Pesach sacrifice that made them worthy of leaving Egypt.
A people that were beaten down as slaves, were in the process of elevation to a level of Adam before the sin of the Garden of Eden.
These last three plagues and the instructions that came with them, gave a loud and clear message. The G-d of Israel is the One true G-d, and He alone is worthy of worship.