The fluid solve is incompressible which will avoid velocities that are divergent from a point.
Depending on what you are after you could perhaps use an emitter with spherical bounds and low dropoff then keyframe the emitter to grow in size. Or you could use a radial field, perhaps with volume bounds on the field( although this will still have to fight against the fluid incompressibility ). Temperature turbulence may also help. A low solver quality will also relax the incompressibility of the fluid, but will make the animation more diffuse and less interesting.
Duncan