Drilling into Exterior Wall

[Murp]

Hello. I am going to mount a TV in the living room on an exterior wall. All load-bearing walls in the apartment are concrete, including this wall. However, it doesn't sound like a concrete wall when I knock on it, not as solid. All other concrete walls sound the same, but this wall is noticeably different. It is definitely concrete, but there seems to be some layer in between.

My beginner question is:

What am I dealing with here? What makes this wall in the living room different from all other exterior walls in the apartment? The building was constructed in 2003.

 

[Tosse]

Why is it guaranteed concrete?

Try drilling a small hole where there's supposed to be a hole anyway, or drive a nail halfway in and you'll find out.

 

[Murp]

Why is it guaranteed to be concrete?

Try drilling a small hole where you need a hole anyway, or hammer in a nail halfway and you'll find out.

It's an exterior wall so I assumed it was a load-bearing concrete wall. On the apartment plan, it's also shown as thick as the other exterior walls. Is it possible that this exterior wall doesn't need to be concrete?

 

[henke_benke]

It is an exterior wall so I assumed it was a load-bearing concrete wall. On the apartment blueprint, it is also as thick as other exterior walls. Is it possible that this exterior wall therefore does not need to be concrete?

exactly.

 

[Tosse]

It's an exterior wall, so I assumed it was a load-bearing concrete wall. On the apartment plan, it's also the same thickness as the other exterior walls. Is it possible that this exterior wall doesn't have to be concrete?

Absolutely, it's possible.

 

[Murp]

Absolutely, it is possible.

So what does it sound like? Gypsum with wooden studs, and then a plaster facade on the outside of the gypsum?