Given an isoparametric function f on the n-dimensional round sphere, we consider functions of the form u = w • f to reduce the semilinear elliptic problem −∆g 0 u + λu = λ |u| p−1 u on S n with λ > 0 and 1 < p, into a singular ODE in [0, π] of the form w ′′ + h(r)where h is an strictly decreasing function having exactly one zero in this interval and ℓ is a geometric constant. Using a double shooting method, together with a result for oscillating solutions to this kind of ODE, we obtain a sequence of sign-changing solutions to the first problem which are constant on the isoparametric hypersurfaces associated to f and blowing-up at one or two of the focal submanifolds generating the isoparametric family. Our methods apply also when p > n+2 n−2 , i.e., in the supercritical case. Moreover, using a reduction via harmonic morphisms, we prove existence and multiplicity of sign-changing solutions to the Yamabe problem on the complex and quaternionic space, having a finite disjoint union of isoparametric hipersurfaces as regular level sets.