G_2-instantons are a special kind of connections on a Riemannian 7-manifold, analogues of anti-self-dual connections in 4 dimensions. I will start this talk by giving an overview of known examples and why are we interested in them. Then, I will explain how we construct G_2-instantons in SU(2)^2-invariant cohomogeneity one manifolds and give new examples of G_2-instantons on R^4xS^3 and S^4xS^3. I will then discuss the bubbling behaviour of sequences of G_2-instantons found.