If the osmotic pressure of the blood were increased above normal levels, it means that

Hemolysis would occur

Explanation:

If the osmotic pressure of the blood rises too much (normal values are approximately 7.7 atm), it becomes hypertonic (when the red blood cells become turgid) in relation to other compounds, facilitating the passage of other fluids.

For example, if the blood is hypertonic in relation to a certain serum, the water contained in it would start to enter the red blood cells and they would eventually swell, and could burst. This process is known as hemolysis.