R, 140 136 128 124 123 110 bytes

j=1:396/99-2 image(outer(j,j,Vectorize(function(x,y,n=99){while((n=n-1)&abs(F)<2)F=F*F+x+1i*y;n})),c=colors()) 

Try it at rdrr.io

6y after the Q was asked, but I love Mandelbrot sets, and the earlier R solution was 211 characters...