waiting=ExampleData[{"Statistics","OldFaithful"}][[All,2]];

mdist=MixtureDistribution[{1/3,2/3},{GammaDistribution[a,b],GammaDistribution[c,d]}];
edist=EstimatedDistribution[waiting,mdist,{{a,80},{b,.5},{c,200},{d,0.5}}];

dp=DiscretePlot[PDF[EmpiricalDistribution[waiting],x],{x,DeleteDuplicates[waiting]},Filling->Axis,PlotRange->{{35,100},All},AxesOrigin->{35,0},PlotStyle->Darker@Hue[.908667,.7,.7]];
{Show[dp,Map[SmoothHistogram[waiting,#,PlotRange->{{35,100},All},PlotStyle->Darker@Hue[.908667,.7,.7]]&,{{"Adaptive",Automatic,1},"SheatherJones","LeastSquaresCrossValidation","Oversmooth"}]],Show[dp,Plot[PDF[edist,x],{x,0,100},PlotStyle->{{Darker@Hue[.908667,.7,.7],Thick}},Filling->Axis,FillingStyle->Directive[Opacity[.2],Hue[.908667,.7,.7]],PlotRange->{{35,100},All}]]}//GraphicsRow