The significant jump in ionisation energies is between the 3rd and 4th ionisation energy. Corresponding to a change in energy level (orbital) at the 4th electron being removed. Therefore the element will have 3 electrons in its outer shell.
So you find the element in group 3. Aluminium. Which as an electron configuration of 2,8,3. You can see from the configuration that it supports the pattern of ionisation energies.