"Tell me about it" is a tainted phrase. It is impossible to use without it sounding insincere. Whenever we see it, we interpret it as "I strongly agree" or "I also have a similar story." And, in all fairness, that is how it's used almost every time. But you can do more with it.
"Tell me about it" is a simple phrase. It asks for more information, maybe even a story. It's a lovely way to implore.
If you are working in an audio medium, the right tone of voice can give the proper context. And if you are in a visual medium, the right body language can also show it right. It is mostly in prose where it becomes more difficult.
Of course, just because it is difficult does not mean that it's impossible, nor does it mean that it's worthless.