Combined measurements of fluctuation spectroscopy and weak nonlinear transport of the semimetallic ferromagnet EuB 6 reveal unambiguous evidence for magnetically driven electronic phase separation consistent with the picture of percolation of magnetic polarons (MP), which form highly conducting magnetically ordered clusters in a paramagnetic and "poorly conducting" background. These different parts of the conducting network are probed separately by the noise spectroscopy/nonlinear transport and the conventional linear resistivity. We suggest a comprehensive and "universal" scenario for the MP percolation, which occurs at a critical magnetization either induced by ferromagnetic order at zero field or externally applied magnetic fields in the paramagnetic region. © 2012 American Physical Society.