A laptop adapter is the main powering system of your laptop, but it always goes hot when you touch it. Don’t worry about that it is normal, it converts AC electricity from the electrical plug into a DC electricity. Which used to charge the laptop battery or running the laptop if you removed the battery.
The heats produced is disposed of through that high temperature which you could feel when you touch it.
Most of the electricity sources are AC (Alternating Current) except the batteries are DC sources. The laptop adapter performs a transformation of AC electricity 110/220 V to a lower DC value (9,12,14…). So the amount of electricity lost in this process is transformed into heat which causes the adapter to be hot.
Since it contains electric dissipation elements like resistors, this process follow the fundamental of energy-saving ( total input energy = total output energy ).
Also, the heat produced in the AC-DC converting process must be disposed of. the most effective heat sink is the Fluids (water or air). Because of that your laptop has a fan and heat sink pins.
But in the adapter case, there is no disposal of the heat so they heat transferred to the case from the air inside the close adapter. The plastic case of the adapter will get hotter as long as it works.
If you touched the adapter anytime and it was cold you should know that it is not working fine. If you think that your laptop adapter is very hot, just unplug it and put it toward the air stream, it will cool down.
Finally, laptop adapter heat increment is normal, it occurs because it lowers the electricity level , also because it has not effective heat sink structure, so don’t be confused.