I had my tires and washer liquid tank replaced few weeks ago and I don't know if it has anything to do with that.
Last few days, some weird liquid is dripping from the bottom of the car.
any idea?

 

Is your battery located in front of the passenger seat, because the only thing I can think of that makes crystals is sulfuric acid

 

looks like moisture and carbon (soot) from your exhaust finding a low spot during cold starts or cold idle and dripping from the exhaust sections.. I cant tell you how many times I have moved cars around in my shop and had them leave little spots like this.. Its normal.