On a large scale, if vast quantities of matter in the universe did (by mutual attraction), collapse to a small volume, ‘bounces’ would occur giving ‘bangs’. The mechanism for the ‘bounce’ is the reduction in gravitational mass.
According to

(see galactic rotation curves)

For a collapsing supercluster the strength of the gravitational constant depends on the radius of the matter in the universe. If the radius reduced, G would decrease. As density and temperatures increased all matter would be in plasma form. The pressure of this plasma would increase as the radius decreased.

There would come a time when the outward pressure was greater than the inward force of gravity. The collapse may continue however, due to momentum, but slow down. The pressure would increase further and the strength of gravity would continue to decrease and then the ‘bang’ would occur giving the foam type of large scale structure.

The cosmic microwave background radiation and the abundances of the elements are two major successes of Big Bang cosmology. The predictions of standard Big Bang cosmology could be mimicked by this situation.