Dissolving the tar with mineral spirits (or any other solvent is a bad idea).

Brick is porous, and the tar laden mineral spirits will be wicked into the brick causing a permanent stain you'll never get out.

I agree with the advice to chip it off the brick in winter if your winter are cold enough to freeze the tar so that it's brittle.

Then use a sandblaster in summer to remove any tar that didn't come off in winter.

If it's roofing "tar", then it's asphalt.

Asphalt is produced from refining crude oil. When you've heated the crude oil to drive everything that can be boiled off out of the oil, then what's left in the pot is called "asphalt". Tar is traditionally made from coal and is a byproduct of making coke for the production of iron. Pitch is a byproduct of the incomplete burning of wood to make charcoal. Nowadays, everyone uses asphalt instead.