Why did my flight climb so sharply on takeoff?
Your flight took off during a storm. During a storm, the wind speed close to the surface of the earth is much lower than the wind speed a bit higher up. This variation of wind speed over a short vertical distance is called wind shear. The aircraft is taking off into the wind, so during the initial climb the headwind increases. Increasing headwind during climb does miracles to the climb rate.  

Suppose you want to climb from sea level to 2000 feet while increasing the true airspeed from 140 to 160 knots (70 m/s to 80 m/s).  In steady wind conditions that means the aircraft needs to accelerate 20 knots during that climb, which consumes part of the energy available from the engines. 

But if there is a windshear and the headwind is increasing by 30 knots during that climb (not unreasonable in stormy conditions), the ground speed will reduce by 10 knots. Instead of needing to add kinetic energy, the aircraft needs to reduce it by converting it into potential energy (altitude). This means more energy is available for climbing and thus the climb rate is higher.

The wind reports from the airport at the time of take-off showed a wind of 29 knots (39 knots gusts), almost straight down the runway. 

If you look at the wind profile this morning (I could not access yesterday's data anymore) you see that the wind increases from 20 kts at the surface to 51 knots at 3000 ft. That's a lot of free airspeed the aircraft gets during climb! 



 source: screenshot from windy.com 



 source: screenshot from windy.com 

In addition, the effect of a stormy headwind is that the ground speed is relatively low. This makes the climb much steeper than in the no-wind condition. 



Looking a bit closer at the raw data from FR24, the aircraft took off at 131 knots groundspeed (the first airborne report is 25 ft above the runway). 6 seconds after the first airborne ADS-B report, the altitude had increased by 525 ft. Even if we conservatively assume it took 7 seconds to climb to 500 ft (round-off errors), it requires a vertical acceleration over 1.6 g to achieve that. That must have felt very aggressive! 

The first 2000 ft of climb took only 25 seconds, an average of 4800 ft per minute. The ground speed reduced to 119 knots by the time the aircraft had climbed 2800 ft, 37 seconds after take-off. 

After that, the aircraft had climbed through most of the boundary layer of the earth and the windshear reduced. The rest of the climb was fairly typical. 



It was not only your perception; by all means it was an impressive take-off performance for a B738